Process of producing solutions of cellulose.



UNITE STATES PATENT OFFICE.

EMILE BRONNERT, OF MULHAUSEN, GERMANY.

. PROCESS OF PRODUCING SOLUTIONS- OF CELLULOSE.

SPECIFICATION forming part of Letters Iiatent No. 646,799, dated April 3, 1900. Application filed October 26, 1899. Serial No. 734,869. (No specimens.)

To all whom it may concern.-

Be it known that'I, EMILE BRONNERT, a citizen of Germany,residin g at Niederm'orschweiler, Miilhausen, Germany, have invented a certain new and useful Improvement in Processes of Producing Solutions of Cellulose, (for which I haveapplied for a patent in Great Britain, dated September 9, 1899, No. 18,260, and in Germany, dated August 7, 1899,) of which the following is a specification.

It has been proposed to utilize "solutions of celluloseipgige chlorid solution in the arts. lVyniTahd Powell','English Patent No. 16,805, dated December 22, 1884, dissolve cellulose in zin'c-chlorid solution of specificgravity 1.8 orin a corresponding solution of another zinc I salt,t0 which,if necessary,the chlorid of an alkaline earth has been added, at a temperature of 100 centigrade andex ress the warm solution at high pressure to form Iam ents i31 incandescent lamps 1 and other purposes.

Draper and Tompkins, English Patent No.1

17,901, dated July 30,1897, prepare fine silky threads in nearly the sameway as that described in the Patent No. 16,805. While Wynne and Powells process haspr'oved suc-" cessful for making carbon filaments, Draper. and Tom pkinss process has notb'een applied, the reason beingthat the threads made in this manner have little strength. This lack of strength is due, on the one hand, to the small percentage of cellulose--at highest some four per cent.-contained in the solution, and, on the other hand, to the use of heat in making the solution, which decomposes much of the cellulose. I have found that cellulose is much more easily soluble in concentrated zinc chlorid and that the-thread produced by decomposing the solvent is much stronger if the cellulose is first hydrated by known'methods, then treated with oxidizing agents, or first treated with suitable oxidizing agents and then hydrated and finally dissolved without application of heat.

My invention consists in the application of this discovery, and for this purpose the rap; ma teojal, freed from fat and bleached, isfirst treated for about one hour with a cold concentrated solution of caus tig soda. After it is thoroughly merceied'by thTs treatment it is submitted to centrifugal action, transferred to much water, and washed free from alkali.

, other hydrate of cellulose is next treated with an oxidizing agentadvantageously an electricallyprepared weak bleaching solution containing some two grams of available chlo rin per liter. Other bleaching materials, such as chlorid-of-lime solution and the like, may, however, be used. It will be seen that I heat the material with a weak bleaching solution instead of the energetic bleaching solution containing some five grams of active chlorin per liter, with which it has hitherto been treated for twelve to eighteen hours. The bleached material is next thoroughly washed,

finely divided, if necessary,and witheutw ing dissolved directly in concentratw chlorid without application of heat. When cellulose is used, it may be first treated with an oxidizing agent and then with a hydrating agent. In this manner alight viscous so-- I lution containing. up rdoi' eight percent. of cellulose is "obtaiie d,Wlii6lTisofaonsistence suitable for the-production of thread by a gentlev pressure at the ordinary temperature. j

To produce an artificial thread more nearly app'roachingsilk in its properties than does cellulose thread, natural-silk waste may be dissolved in a concentrated solution of zinc chlorid in the .knownmanner, and the solution may be mixed cold in the necessary proportionwith the cellulose solution prepared as described above. The addition of the silk solution impairs the thread-making properties of the cellulose solution, and it is well to limit the quantity of the silk to about one fifth of that of the cellulose.

Having thus described the nature of this in=' vention and the best means I know of carryingthe same into practicaleffect, I claim- 1. The process herein described for producing solutions of cellulose in concentrated zinc-chlorid solution, which consists in first treating cellulose,freed from fat and bleached,

with concentrated caustic-alkali solution, as

in the mercerizing process, at a low temperature, then submitting it to centrifugal action and Washing it, then treating it with an oxidizing agent, and finally, after again washing and submitting it to centrifugal action, dissolving it directly in concentrated zincchlorid solution.

xo ing and submitting it to centrifugal action,

dissolving it directly in concentrated zincchlorid solution.

In testimony whereof I have hereunto set my hand in presence of two subscribing witncsses.

, EMILE BRONNERT.

Witnesses:

EMMA FETTER, PAUL SCHLUMBERG ER. 

